I have a single USB drive and Ubuntu 18.04 has been installed on it. I want to convert this drive to Linux on USB, meaning that Ubuntu gets installed on the USB drive as a standard installation that is writable and whatnot. How can this be done? When I try to format the USB drive (which has Ubuntu running live from RAM) using GNOME Disks, I get the following message:
Error unmounting filesystem
Error unmounting /dev/sdb: target is busy (udisks-error-quark, 14)
This appears to be because it is not obvious how to unmount the root partition. How should I approach this problem?